Various desktop-based and web-based applications enable users to select from among a variety of pre-defined templates and modify one or more selected templates to generate a document such as a report, a graph, or a chart, or a document that includes one or more graphs or charts. These applications may be collectively referred to as document template applications. The templates may be defined as documents written in standardized protocols, such as Extensible Markup Language (XML). Various applications may include tools such as XML schemas and scripts for interpreting and executing XML documents. However, the potential exists for such tools to enable unsafe operations, such as accessing the file system of a computer or other computing resource. The potential for such unsafe operations may expose a computing environment to inadvertent errors or malicious activity, that may damage or compromise the security of computing resources or of data accessible to those computing resources.